lessthanlights
New member
Is there any reason I cannot put two SCWD on the same closed loop as long as the pump is powerfull enough? I looking to put 4 returns into the tank.
Question for SCWD users.
- Thread starter lessthanlights
- Start date
Ken668
New member
I don't see why you couldn't. I'm actually in the process of installing 3 of these off of a single pump in my prop tank.
The one thing I'm anticipating is a slight pulsing effect when each SCWD is about to switch outputs. I believe both sides are open for a couple seconds and this will releave some head pressure and cause the other SCWDs to drop in output. But then when it closes the one side, the others will return back to normal flow. So if you can, picture 2 or 3 of these pulsing out of sync with each other. I think it will only add to the dynamic of the flow.
As for balancing the flow, assuming all the returns are the same length, etc. the flow should be relatively the same. A ball or gate valve might not be a bad idea if you want to tune the outputs though.
Anyway, let us know how you make out. I'll try to post back once I get mine up and running.
The one thing I'm anticipating is a slight pulsing effect when each SCWD is about to switch outputs. I believe both sides are open for a couple seconds and this will releave some head pressure and cause the other SCWDs to drop in output. But then when it closes the one side, the others will return back to normal flow. So if you can, picture 2 or 3 of these pulsing out of sync with each other. I think it will only add to the dynamic of the flow.
As for balancing the flow, assuming all the returns are the same length, etc. the flow should be relatively the same. A ball or gate valve might not be a bad idea if you want to tune the outputs though.
Anyway, let us know how you make out. I'll try to post back once I get mine up and running.
exoticaquatix
In Memoriam
i would think that with equal plumbing as a given balancing 2 sqwds would be almost impossible. the pressure on either one will constantly be changing. wouldn't there be a swing of pressure back and forth? for the sake of only plumbing your system once i guess you might as well install a valve on each SQWD from the get-go if you can afford EVEN MORE head loss. just my take on it.
-nick
-nick
Ken668
New member
Well, I got my 3 SCWDs fired up. Did not get the pulsing that I expected. They actually perform rather well. Approximately 8-10 second switching for all 3.
exoticaquatix,
From the looks of it, balancing outputs does not seem to be a concern. Looking at each I could not tell that any individual SCWD was putting out a lot more flow than the others. They actually looked exactly the same to the eye.
exoticaquatix,
From the looks of it, balancing outputs does not seem to be a concern. Looking at each I could not tell that any individual SCWD was putting out a lot more flow than the others. They actually looked exactly the same to the eye.
JCURRY@WESKETCH
New member
I ran 2 SCWDs off an Iwaki 40RLT with no problems. Equal flow from both units and each port. I had valves on each unit but never had to touch them.
I just recently hooked up one of these scwd when we installed a sump on a friends tank. It was different than I thought, pulsing for like 8-10 seconds and creating a lot of air bubbles. I really thought it was junk and would reccomend something different in the way of a making a mixed current.
myakkareef
Premium Member
SCWDS are a great inexpensive current switcher. If you had bubbles, IMHO it was not from the scwd. I have run them for many years and have had overall good luck. The current one has been running for almost 2 years and has never been cleaned or serviced. With that said it will probably die tonight...
lessthanlights
New member
For those who have multiple sqwd do you have any pics? I'm still deabting between the cheaper sqwds and the bank breaking Ocean Motion 4-ways.
JCURRY@WESKETCH
New member
No pics since I removed my SCWDs to install an OM SS.
exoticaquatix
In Memoriam
what i ment was that as soon as you try to restrict one it will affect the other(more flow) . is your plumbing symmetrical for the most part? if so i was thinking they would all be pretty much the same but there would be a slight shift from scwd to scwd as they cycled. you seem to be having good results but what kind of flow do you think your getting, % wise i mean. what is your total flow loss from scwds and head pressure?
-nick
-nick
CoolUsername
New member
I have a single SCWD that I just recently did the "Another SCWD MOD" on:
http://reefcentral.com/forums/showthread.php?s=&threadid=843091
With this mod you can see inside the scwd. The transition from one side to the other is smooth and allows for total outlet size to remain constant (in the middle one side is open 50% the other side 50%). So you would not expect any significant back pressure on the SCWD input during a transition. In fact the BP should remain constant. So plumbing two (or more) in parallel would in fact operate as JCURRY@WESKETCH and Ken668 observed - no surge effects between SCWDs.
I do recommend this mod. It took about an hour to do and cost about $3.50. Everything was purchased a the local HW store. I didn't replace the spin valve as the thread suggests, I did I just repaired and reinforced the existing one. Now I can open and clean out my SCWD. There are a lot of ideas there about uping the flow capability of a SCWD if your interested.
http://reefcentral.com/forums/showthread.php?s=&threadid=843091
With this mod you can see inside the scwd. The transition from one side to the other is smooth and allows for total outlet size to remain constant (in the middle one side is open 50% the other side 50%). So you would not expect any significant back pressure on the SCWD input during a transition. In fact the BP should remain constant. So plumbing two (or more) in parallel would in fact operate as JCURRY@WESKETCH and Ken668 observed - no surge effects between SCWDs.
I do recommend this mod. It took about an hour to do and cost about $3.50. Everything was purchased a the local HW store. I didn't replace the spin valve as the thread suggests, I did I just repaired and reinforced the existing one. Now I can open and clean out my SCWD. There are a lot of ideas there about uping the flow capability of a SCWD if your interested.
Ken668
New member
I performed this same mod to all three of my SCWDs. In my mind, the company should look at creating some version of this in a future design. Allow it to be maintained and open up the inlet and outlets for better flow. But like CoolUser said, it's a great mod, VERY easy to do, and dirt cheap.
Anyway, I'll try to get a picture of my tripple SCWD setup when I get home from work later.
Anyway, I'll try to get a picture of my tripple SCWD setup when I get home from work later.
rljlll
New member
here is proof multiple SQWDs works
http://reefcentral.com/forums/showthread.php?s=&threadid=920738&perpage=25&pagenumber=3
http://reefcentral.com/forums/showthread.php?s=&threadid=920738&perpage=25&pagenumber=3
Last edited:
CoolUsername
New member
according the scwd mfr web site:
http://www.3iqventures.com/index.html
The max gauranteed pressure rating is 5 PSI.
The flow rate chart the list only goes so high:
Flow into SCWD Switching
SCWD Output Efficiency Duration
150 gph 90 gph 60% 22 seconds
180 gph 120 gph 65% 16 seconds
240 gph 180 gph 75% 12 seconds
270 gph 210 gph 80% 10 seconds
330 gph 240 gph 80% 9 seconds
400 gph 360 gph 90% 7 seconds
600 gph 540 gph 90% 5 seconds
720 gph 660 gph 90% 4 seconds
And finally the inside diameter of the inlets and outlets is 1/2" which compares to standard 3/8" schedule 40 PVC pipe.
http://www.gizmology.net/pipe.htm
Which is probably your biggest flow restrictor. There are mods to increase the size of the inlets/outlets. There are also mods to increase flow in different ways. Check the following thread:
http://reefcentral.com/forums/showthread.php?s=&threadid=843091&perpage=25&pagenumber=1
I know i didn't really answer the question, but I think you can read between the lines that the chart only goes so high for a reason.
Similar threads
